Low angle, dual port light coupling arrangement

ABSTRACT

A compact coupling arrangement between a light source and a plurality of light distribution harnesses includes a plurality of reflector members arranged around the light source with respective focal points of the reflector members positioned substantially coincident with the light source, so as to receive light from the source and reflect the light away from the source. Further included is a plurality of light coupling members, each having an inlet and an outlet surface for receiving light originating from the light source and transmitting light, respectively. A plurality of light distribution harnesses is provided for respectively receiving light from the light coupling members. The light coupling members each comprise a lens having a negative curvature in at least one direction generally transverse to a main light transmission axis therethrough, for receiving light at a first angular distribution and transmitting light at a reduced angular distribution. To facilitate manufacturing, at least one of the light coupling members may comprise an integral portion of one of the reflector members coinciding with the curvature of a proximate reflector member. Further, at least one of the inlet and outlet surfaces of one of the coupling members may be non-axisymmetrical about the main light transmission axis of its associated coupling member, for improving efficiency of light coupling.

CROSS-REFERENCE TO RELATED APPLICATION

This is a division of application Ser. No. 08/607,529, filed on Feb. 27,1996 as U.S. Pat. No. 5,826,963.

The present application is related to application Ser. No. 08/116,146,entitled "An Improved Optical Coupling Arrangement Between a Lamp and aLight Guide," filed on Sep. 2, 1993, by J. M. Davenport et al., andassigned to the same assignee as the present application.

FIELD OF THE INVENTION

The present invention relates to an arrangement for coupling lightbetween a light source and one or more light distribution harnesses suchas light guides. More particularly, the invention relates to theforegoing type of light coupling arrangement wherein light is coupledinto the light distribution harness at a low cone angle such as 60degrees.

BACKGROUND OF THE INVENTION

The present invention relates to arrangements for coupling light at highefficiency between a light source and one or more light distributionharnesses, such as lenses or light guides. For instance, it is desirableto feed light into readily available light guides having numericalapertures of between 0.4 and 0.65. As used herein, a numerical apertureof 0.5 is obtained where 90 percent of the light is contained within a60-degree cone angle. The above crossreferenced application to J. M.Davenport et al. describes and claims arrangements for efficientlycoupling light from a high brightness light source, such as a xenonmetal halide high pressure discharge lamp or a halogen lamp, to lightguides or other distribution harnesses. In one of the embodimentsdisclosed, elliptical reflectors focus light through tapered rods intolight guides. The tapered rods receive light at one angular distributionat their smaller ends, and transmit light at a lower angulardistribution through their larger ends. This achieves a so-calledangle-to-area conversion that beneficially enables the use of lightguides having numerical apertures in the mentioned range.

It would, however, be desirable to provide further light couplingarrangements that employ different optical elements to achieve areduction in angular distribution of light transmitted to a lightdistribution harness. It would also be desirable if embodiments of lightcoupling arrangements using such different optical elements could bemanufactured more easily than embodiments using tapered rods.

SUMMARY OF THE INVENTION

An object of the invention, accordingly, is to provide light couplingarrangements employing optical elements other than tapered rods toachieve a reduction in angular distribution of light transmitted to alight distribution harness.

A further object of the invention is to provide embodiments of lightcoupling arrangements of the foregoing type that can be manufacturedmore easily than embodiments using tapered rods.

In accordance with the invention, there is provided a compact couplingarrangement between a light source and a plurality of light distributionharnesses. The arrangement includes a plurality of reflector membersarranged around the light source with respective focal points of thereflector members positioned substantially coincident with the lightsource, so as to receive light from the source and reflect the lightaway from the source. Further included is a plurality of light couplingmembers, each having an inlet and an outlet surface for receiving lightoriginating from the light source and transmitting light, respectively.A plurality of light distribution harnesses is provided for respectivelyreceiving light from the light coupling members. The light couplingmembers each comprise a lens having a negative curvature in at least onedirection generally transverse to a main light transmission axistherethrough, for receiving light at a first angular distribution andtransmitting light at a reduced angular distribution.

To facilitate manufacturing, at least one of the light coupling membersmay comprise an integral portion of one of the reflector memberscoinciding with the curvature of a proximate reflector member. Further,at least one of the inlet and outlet surfaces of one of the couplingmembers may be non-axisymmetrical about the main light transmission axisof its associated coupling member, for improving efficiency of lightcoupling.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing, and further, objects and advantages of the invention willbecome apparent from the following description when read in conjunctionwith the drawings, in which like reference characters designate like orcorresponding parts throughout the several views, and in which:

FIG. 1 is a side plan view in section of a light coupling arrangement inaccordance with the present invention.

FIG. 1A is a simplified side plan view in section of a pair of lightcoupling arrangements respectively with and without a negative lens,with superimposed ray tracings to illustrate an important principle ofthe present invention.

FIG. 2 is detail, side plan view of an alternatively shaped lens thatmay be used in the light coupling arrangement of FIG. 1.

FIG. 3 is a detail, side plan view of a lens positioned further to theright of the adjacent reflector portion than as shown in FIG. 1.

FIG. 4 is a detail, side plan view of a lens positioned further to theleft of the adjacent reflector portion than as shown in FIG. 1.

FIG. 5 is a detail, side plan view of an alternatively shaped lens thatmay be used in the light coupling arrangement of FIG. 1.

FIG. 6 is a detail, side plan view of a coupling member that may be usedas an alternative to the lenses described in connection with FIG. 1, forinstance.

FIG. 7 is a top plan view in section of a light coupling arrangement inaccordance with a further embodiment of the invention that employs threenegative lenses.

FIG. 8 is a side plan view in section of a light coupling arrangement inaccordance with a still further embodiment of the invention that employsnonsymmetrically arranged lenses.

FIG. 9 is a side plan view in section of a light coupling arrangement inaccordance with another embodiment of the invention also employingnonsymmetrically arranged lenses.

FIG. 9A is a graphical depiction of a portion of a light distributionfrom a light source used in the embodiment of FIG. 9.

FIG. 10 shows a side plan view (at the top) and a top plan view (at thebottom) of a light coupling arrangement in accordance with a furtherembodiment of the invention.

FIG. 10A is a simplified side plan view in section of a side view (atthe top) and a top view (at the bottom) of a light coupling arrangementusing biconic negative lenses and biconic reflectors, and withsuperimposed ray tracings to illustrate a principle of the presentinvention.

FIG. 10B is similar to FIG. 10A, but shows the light couplingarrangement without lenses, and with superimposed ray tracings toillustrate deficient operation.

FIG. 11 is a side plan view in section of a light coupling arrangementin accordance with yet another embodiment of the invention in which areflective coating is disposed on a vitreous envelope of a light source.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a light coupling arrangement 10 according to a preferredembodiment of the present invention. Because the left and right sides ofarrangement 10 as shown in FIG. 1 are typically symmetrical with eachother, for brevity the following description focusses more on one sidethan the other. Arrangement 10 comprises a pair of reflectors 12 and 14which, collectively, surround a light source 16 and, for this purpose,may be each ellipsoidal in shape. Reflector 12 reflects light fromsource 16 to a lens 18 positioned in the wall of reflector 14.Similarly, reflector 14 reflects light from source 16 to a lens 20positioned in the wall of reflector 12. Looking from the right or leftin FIG. 1, lenses 18 and 20 would appear circular.

Light source 16, schematically shown as a point, preferably comprises ahigh brightness, high pressure discharge light source. Light source 16may comprise the light source described and claimed in U.S. Pat. No.5,239,230, issued on Aug. 24, 1993 to Mathews et al., assigned to thesame assignee as the present invention, and herein incorporated byreference in its entirety. Such light source is capable of providing alight output in the range of greater than 4000 lumens from an arc gap ofapproximately 2.5. By way of example, light source 16 couldalternatively comprise a high brightness halogen light source.

The interior of reflectors 12 and 14 are respectively coated withreflective coatings 12A and 14A, which, however, do not cover lenses 18and 20. Such reflective coating may comprise an optical interferencefilter formed from alternating layers of high and low index ofrefraction material. Such filters can be designed to reflect visiblelight, but transmit infrared light, for instance. Typical pairs ofalternating high and low index of refraction material comprise tantalaand silica, niobia and silica, titania and silica, or hafnia and silica.The number of layers typically may be above 15, e.g. 24. Borate maskingcan be used to pattern reflective coatings 12A and 14A so as not tocover lenses 18 and 20. Further details of the foregoing opticalinterference coating may be found in co-pending application Ser. No.08/165,447, filed Dec. 10, 1993, assigned to the instant assignee, andherein incorporated by reference.

Further, the interior surfaces of reflectors 12 and 14 may be faceted,as is known per se in the art, to create a more spatially uniform lightdistribution.

Reflectors 12 and 14 each have two focal points. Respective first focalpoints of the reflectors substantially coincide with light source 16.Typically the coincidence is virtually total, but the invention yieldssubstantially the same benefits where the coincidence is not total butis sufficient to achieve a substantial coupling of light from source 16to lenses 18 and 20. As used herein, such condition of substantialcoupling of light occurs when respective focal points of the reflectors"substantially coincide" with each other. A second focal point forreflector 12 is shown as point 19. Inlet surface 18A of lens 18 ispositioned between light source 16 and second focal point 19, so as tocreate a modified, effective second focal point 19'. Similarly, a secondfocal point for reflector 14 is shown as point 21. Inlet surface 20A oflens 20 is positioned between light source 16 and second focal point 20,so as to create a modified, effective second focal point 21'.

Inlet surfaces 22A and 24A of light distribution harnesses 22 and 24 arepreferably positioned at modified, effective focal points 19' and 21' ofthe reflectors. The harnesses guide light received from source 16 toremote optics (not shown) such as automobile headlamps, or lighting indisplay cases in stores. As shown, harnesses 22 and 24 may compriselight guides formed, for instance, of a bundle (not shown) of opticallight conductors. Further details of light guides are provided in U.S.Pat. No. 5,341,445 issued to J. Davenport and R. Hansler (also presentinventors), and assigned to the present assignee. Other types of lightdistribution harnesses may be used, such as lenses, fold mirrors, lenssystems, mixing rods, and prisms. For instance, a mirror could be placedat point 19', in lieu of harness 22, to force light back through lightsource 16 and into harness 24.

Light guides 22 and 24 are respectively spaced from their associatedlenses 18 and 20 by a distance D. Such distance is sufficient tothermally isolate the light guides from lenses 18 and 20, whosetemperature increases when light source 16 is powered, and its selectionwill be apparent to those of ordinary skill in the art. Spacing D alsopermits insertion of a light modulator 150 (shown in phantom), such as acolor filter or light-blocking member, into any of the paths of lightshown, so as to modulate the color or the on/off condition of light atthe remote optics (not shown).

In accordance with an aspect of the present invention, lenses 18 and 20comprise negative, or diverging lenses. Negative lenses receiveconverging light at a first angular distribution and transmit light at areduced, converging angular distribution. Thus, light received at inputsurfaces 18A and 20A of the lenses an angular distribution of, e.g., 53degrees, is converted to a reduced angular distribution at outletsurfaces 18B and 20B of the lenses of, e.g., 37 degrees. This enablesthe use of light guides 22 and 24 with readily available numericalapertures. As used herein, a numerical aperture of 0.5 is obtained where90 percent of the light is contained within a 60-degree cone angle.Light guides with numerical apertures in the range of 0.4 to 0.65 arereadily available.

FIG. 1A illustrates the function of a negative lens in accordance withthe invention. In FIG. 1A, light coupling arrangement 10 includesnegative lenses 18 and 20; light coupling arrangement 10' does not. Asshown, ray tracings from reflector 12 of arrangement 10', which lacksthe negative lenses, converge to the right of the arrangement at line11', at a focal point of the reflector. Ray tracings from reflector 12of arrangement 10, which includes negative lenses, converge to the rightof the arrangement at line 11, at a modified, effective focal point ofthe reflector. This is due to the action of negative lens 18, whichcreates the modified, effective focal point of reflector 12. As can beappreciated from the ray tracings in the figure, the angulardistribution of the ray tracings that pass through negative lens 18 isbeneficially less than the angular distribution of the ray tracingsprovided by arrangement 10'.

In its broadest meaning herein, a negative lens is intended to include alens having a negative curvature in at least one direction generallytransverse to a main light transmission axis, for receiving light at afirst angular distribution and transmitting light at a reduced angulardistribution. Such a lens could include a non-negative curvature inanother (e.g. orthogonal) direction, and at least one or both of theinlet and outlet surfaces of such lens could be curved to implement thenegative lens function.

Typically, inlet surfaces 18A and 20A of lenses 18 and 20 are concave,and axisymmetrical about an axis 26 that is shown in FIG. 1 as extendingto the right and left, and as coincident to main light transmission axesof lenses 18 and 20. Inlet surfaces 18A and 20A may have, as analternative to the curves shown, a so-called axicon shape. Such a shapehas been found effective to fill in the 0-degree angle light passed tolight guide 22. A particular example of an axicon shape is shown in FIG.2 for a lens 18. As shown, lens 18 comprises a concave, conical surfacethat is axisymmetrical about axis 26.

Returning to FIG. 1, outlet surfaces 18B and 20B are preferably flat, toallow easy manufacturing by pressing or polishing. However, outletsurfaces 18B and 20B can have other shapes and still function accordingto the present invention. The upper and lower boundaries of lenses 18and 20 are shown as dashed lines. This is to indicate that the lensescould be formed integrally with reflectors 14 and 12, respectively, forease of manufacturing, or they could be comprise separately formedparts. (Such dashed lines as appear in association with the lenses inthe further figures all have the foregoing property.) Where reflectors12 and 14 are ellipsoidal in shape, a particularly preferred embodimentis obtained where the curvature for lenses 18 and 20 coincides with thecurvature of the adjacent reflectors. This condition is shown in FIG. 1,and simplifies the manufacturing of the reflectors; for instance, thepatterning of the reflective coatings 12A and 14A tolerates somevariation, with a larger opening resulting in larger lenses, and asmaller opening resulting in a larger reflecting area Such a conditionis obtained according to the following equations for a numericalaperture of 0.5 of the distribution of light from the lenses:

    x.sup.2 /a.sup.2 +y.sup.2 /b.sup.2 =1; a.sup.2 =b.sup.2 +c.sup.2 ; a/c≈2.5,                                          (eqs. 1)

where, for each ellipsoidal shape, the major axis is 2a; the minor axis,2b; x and y are the two orthogonal dimensions; a, b, and c areconstants, with 2c being the separation between the two foci of anellipse; and a numerical aperture as defined above. Preferably, theratio of a/c is between about 2.0 and 3.0 for an elliptical reflector.

Referring to FIG. 3, in contrast with lens 18 of FIG. 1, lens 18 of FIG.3 is shifted to the right, as shown. Referring to FIG. 4, in contrastwith lens 18 of FIG. 1, lens 18 of FIG. 4 is shifted to the left, asshown. As with the embodiment of FIG. 1, lens 18 of FIGS. 3 and 4 can beformed integrally with, or as separate from, reflector 14, as indicatedby the dashed-line upper and lower boundary between the lens andreflector.

In contrast to the curvature of inlet surface 18A of lens 18 as shown inFIG. 1, the curvature of lens inlet surface 18A may be different fromthat of its adjacent reflector. FIG. 5 shows a more accentuatedcurvature for inlet surface 18A of lens 18. As with the embodiment ofFIG. 1, lens 18 can be formed integrally with, or as separate from,reflector 14, as indicated by the dashed-line upper and lower boundarybetween the lens and reflector.

FIG. 6 shows the use of an elongated coupling member 18' rather than themore compact lens 18 as shown in FIG. 1. Inlet surface 18A' of couplingmember 18 is curved in concave fashion in similar manner as the curve oflens inlet surface 18A shown in FIG. 1. Accordingly, coupling member 18`functions as a negative lens as described above, to reduce the angulardistribution of light it transmits to light harness 22 compared to theangular distribution of light it receives at inlet surface 18A`.Coupling member 18' may be sufficiently long to provide the necessarythermal isolation from heat from light source 16 such that its outletsurface 18B' terminates in direct proximity to the second focus ofreflector 12 (shown in FIG. 1) where inlet surface 22A of the lightharness is preferably positioned. Coupling member 18' may be modified inthe above-described manners of modifying lens 18 of FIG. 1, forinstance, by making inlet surface 18A' have an axicon shape.

FIG. 7 shows an arrangement 30 for coupling light from light source 16to three light distribution harnesses 32, 34 and 36. Reflector 38 has afirst focal point preferably coincident with light source 16 and asecond focal point 39 positioned further away from the light source. Aninlet surface 40A of a lens 40 is positioned between light source 16 andsecond focal point 39. Lens 40 functions in the manner described abovefor lens 18 or lens 20. Reflector 42 interacts with lens 44 in the samemanner as reflector 38 interacts with lens 40 as just described.Similarly, reflector 46 interacts with lens 48 in the same manner asreflector 38 interacts with lens 40 as just described. Reflectors 38, 42and 46 may be ellipsoidal in shape. The various parts of arrangement 30function in the same manner as the like-named parts mentioned above.

FIG. 8 shows an arrangement 50 employing a negative lens 20 betweenreflector portions 52 and 54, a negative lens 118 between reflectorportions 56 and 58, and a negative lens 119 between reflector portions58 and 59. In this arrangement, the mentioned lenses are arrangednon-symmetrically about light source 16. Lenses 118 and 119, forinstance, may be used to provide illumination for the right and leftheadlamps of an automobile, while lens 20 provides illumination for theinterior of such automobile. In the illustrated embodiment, lenses 118and 119 could be, for example, closer to a cylindrical lens than to astandard spherical lens. For example, a biconic lens might be used,which has different curvatures in two different orthogonal directions.More broadly, however, one or more of the inlet 118A, 119A or outlet118B, 119B surfaces of lenses 118 and 119 could be non-axisymmetricalabout respective axes 118' and 119' that are aligned with the main pathsof light transmission through the lenses. For instance, lenses 118 and119 could have different curvatures in two different, non-orthogonaldirections. In contrast, lens 20 would typically be axisymmetrical alongaxis 20' aligned with a main path of light transmission through thelens. As with the prior embodiments, e.g., FIG. 1, light harnesses (notshown) are used to distribute the light they receive from the lenses toremote optics (not shown).

FIG. 9 shows an arrangement 60 including a pair of negative lenses 18and 20 as in FIG. 1. However, the lenses in the arrangement of FIG. 9are disposed more downwardly as shown than the corresponding lenses inFIG. 1. This is to accommodate for an asymmetrical distribution of lightfrom light source 16. FIG. 9A shows such an asymmetrical lightdistribution in a graphical depiction of a section of the right halfonly of light distribution 62 of light source 16. Light distribution 16has a generally toroidal shape about an axis 64. However, it has agreater lumen output oriented above the light source, than below it. Tomost effectively couple light from light source 16, lenses 18 and 20 arecorrespondingly located below light source 16. Lenses 18 and 20typically will be axisymmetrical about axes 18' and 20', respectively,aligned with main paths of light transmission through the lenses.

FIG. 10 shows a side plan view (top of figure) and a top plan view(bottom of figure) of an arrangement 70. In this arrangement, reflectors12 and 14 each have a biconic shape with major x, y, and z axes anddimensions h₁ and h₂ as shown in the drawing. A modified, effectivefocal point of reflector 12 is shown as point 72, and a modified,effective focal point of reflector 14 is shown at point 74. The explicitquartic form of a biconic surface is:

    x=(z.sup.2 /r+y.sup.2 /r.sub.2)/(1+√(1-ez.sup.2 /r-e.sub.2 y.sup.2 /r.sub.2))                                                (eq. 2)

Using the following definitions:

    r=a/b.sup.2 ; r.sub.2 =a.sub.2 /b.sub.2.sup.2 ; e=1/a; and e.sub.2 =1/a.sub.2                                                (eqs. 3)

allows the biconic equation to approximate the typical ellipse equationsin the two orthogonal axes:

    x.sup.2 /a.sup.2 +z.sup.2 /b.sup.2 =1; x.sup.2 /a.sub.2.sup.2 +Y.sup.2 /b.sub.2.sup.2 =1                                         (eqs. 4)

    a-c=w/2=a.sub.2 -c.sub.2 ; h.sub.2 ≠h.sub.1          (eqs. 5)

    c=square root of (a.sup.2 -b.sup.2)                        (eq. 6)

    c.sub.2 =square root of (a.sub.2.sup.2 -b.sub.2.sup.2)     (eq. 7)

where w and 2f are constant; variables a, b, and c (not shown) asdefined above in connection with eqs. 1, with a, b and c pertaining tothe curvature of the reflectors as shown in the upper side of thefigure, and with a₂, b₂, and c₂ as shown in the lower side of thefigure. For the system illustrated, the light source is convenientlylocated such that a-c=a₂ -c₂. Accordingly, the second focus of thereflectors in the two orthogonal planes is different, but the firstfocus, where the light source is located, is the same.

In the embodiment of FIG. 10 as described, the reflectors have differentcurvatures in the two orthogonal x-y and x-z planes, but both curveshave a common focus coincident or substantially coincident with lightsource 16 shown as a point. Accordingly, the angular distributions oflight in the two orthogonal planes will be different, and will not havesecond foci that are coincident. This will be advantageous in somedesigns, such as where the light distribution of light source 16 istoroidal in shape and substantially symmetrical about a central axis ofsuch shape. Such shape contrasts with the light distribution shown inFIG. 9A, for instance, which produces substantially more light abovelight source 16 than below it.

In the embodiment of FIG. 10 as described above, lenses 18 and 20 may bebiconic also, i.e., having different curvatures in two differentorthogonal directions. Thus, lenses 18 and 20 appear flat on both oftheir sides as viewed in the upper side of FIG. 10, but curved in theview of the lower side of the figure. The curvature is needed to form anegative curvature in the one case to obtain a lower angulardistribution of light in the associated direction, whereas in the otherdirection the angular distribution need not be decreased so that nonegative curvature is needed in such direction.

Although the reflectors and the lenses of the embodiment of FIG. 10could be biconic as described, they could alternately have differentcurvatures in two axes that are non-orthogonal to each other, such as at80 degrees to each other. The reflectors, however, still would have acommon axis coincident or substantially coincident with light source 16.

FIG. 10A shows in simplified form a side plan view (top of figure) and atop plan view (bottom of figure) of arrangement 70 of FIG. 10. Lightfrom light source 16 is uniform in the x-y plane, but there is verylittle light along the z axis. Such a condition occurs with the toroidaldistribution mentioned above in connection with FIG. 10. In the sideplan view (top of figure), the lens radius is ∞, the ratio a/c is 2.4,and the quantity a-c is 19.5, a and c being defined above in connectionwith eqs. 1. In the top plan view (bottom of figure), the lens radius is-22 mm, the ratio a/c is 2.55 and the quantity a-c is 19.5.

By using a biconic lens 18 with a curvature in the plane of the upperplan view (bottom of figure) of FIG. 10A, the second focal point ofreflector 12 is adjusted to be positioned along line 76, rather thancloser to the reflector. The negatively curved lens 18 in the plane ofthe lower view is desirable also to reduce the angular distribution oflight transmitted from the lens. On the other hand, as the ray tracingshows for plan view (top of figure) of FIG. 10A, the angle of lighttransmitted through lens 18 is naturally low, since there is very littlelight produced along the z axis. With biconic lens 18 having nocurvature in the plane of the upper view of FIG. 10A, the second focalpoint of reflector 12 coincides with line 76. This enables efficientcoupling of light to a light distribution harness (not shown) placed toreceive light at line 76.

FIG. 10B is similar to FIG. 10A, with the mentioned conditions applying,but the arrangement 70' shown lacks lenses. As can be appreciated, amismatch occurs in the location of the second focal points for the sideplan (top of figure) and top plan (bottom of figure) view, respectively.Line 78 passes through the second focal point for lens 12 in the topplan view (bottom of figure), but the second focal point for lens 12 inthe side plan view (top of figure) is located to the right of the line.The angular distribution of light in the top plan view (bottom offigure) is also high. The use of the biconic lens in connection withFIG. 10A resolves both of the foregoing problems, resulting in moreefficient light coupling into light distribution harnesses.

FIG. 11 shows a high intensity light source 116 having electrodes 80 and82 that are spaced by a gap 84 at which light is generated due to an arcdischarge in a gaseous medium (not shown) contained within a sealedchamber 116A of a vitreous envelope 116B. Envelope 116B is coated withan interference coating 86, shown by cross-hatching, except at surfaces118B and 120B, where light is allowed to exit from the light source.Coating 86 is interiorly reflecting to visible light, and preferablytransmissive to infrared light. Coating 86 may be considered to comprisea portion, or member, 112, shown to the left of electrodes 80 and 82,and a portion, or member, 114, formed to the right of the electrodes. Asshown, exterior surfaces 118B and 120B are flat, in which case theinterior surfaces 118A and 120A adjacent exterior surfaces 118B and120B, respectively, are curved to create negative lenses betweenadjacent surfaces 118B, 118A and 120B, 120A Exterior surfaces 118B and120B, however, could be curved to implement negative lenses between theforegoing, adjacent surfaces. Preferably, interior surfaces 118A and120A have a curvature that coincides with (i.e., matches), thecurvatures of the reflector portions 114 and 112, respectively.

The similarity in the reference numerals as between the embodiment ofFIG. 11 and the prior embodiments is intended to signify that theabove-described principles of the invention apply also to the embodimentof FIG. 11. Moreover, the embodiment of FIG. 11 is not limited to anelectroded light source, as shown, but also applies to electrodelesslight sources.

While the invention has been described with respect to specificembodiments by way of illustration, many modifications and changes willoccur to those skilled in the art. It is, therefore, to be understoodthat the appended claims are intended to cover all such modificationsand changes as fall within the true scope and spirit of the invention.

What is claimed is:
 1. A compact coupling arrangement between a highbrightness light source and a plurality of light distribution harnesses,said arrangement comprising:(a) a plurality of reflector membersarranged around said light source with respective focal points of saidreflector members positioned substantially coincident with said lightsource so as to receive light from said source and reflect said lightaway from said source (b) a plurality of light coupling members, eachhaving an inlet and an outlet surface for receiving light originatingfrom said light source and transmitting light, respectively; and (c) aplurality of light distribution harnesses for respectively receivinglight from said light coupling members; (d) said light coupling memberseach comprising a lens having a negative curvature in at least onedirection generally transverse to a main light transmission axis of saidcoupling member, for receiving light at a first angular distribution andtransmitting light at a reduced angular distribution; (e) at least oneof the inlet and outlet surfaces of one of said coupling members beingnon-axisymmetrical about the main light transmission axis of itsassociated coupling member.
 2. The arrangement of claim 1, wherein saidlight coupling member comprises a biconic lens along its main lighttransmission axis.
 3. The arrangement of claim 2, wherein said reflectormembers each has a biconic shape.